Tapered roller bearing · 303 series
30311 bearing
55 × 120 × 31.5 mm
The 30311 is a tapered roller bearing with a 55 mm bore, 120 mm outside diameter and 31.5 mm total width. Medium series with steeper sections for heavier loads.
- Bore d
- 55 mm 2.1654 in
- Outside diameter D
- 120 mm 4.7244 in
- Total width T
- 31.5 mm 1.2402 in
- Cone width B / cup width C
- 29 / 25 mm
- Dimension series
- 03
- Load directions
- Heavy combined radial and axial (one direction per bearing)
Designation explained
What 30311 means
Standard bearing numbers encode the type, the dimension series and the bore. Anything after the base number — seals, clearance, cage — is a suffix.
| Part | Meaning |
|---|---|
3 | Tapered roller bearing |
03 | Dimension series 03 (ISO 355) |
11 | 11 → 55 mm bore (11 × 5) |
Variants
Common 30311 variants
Suffixes change the bearing without changing its boundary dimensions. The exact letters differ between manufacturers — always order by the full designation from the maker you choose.
| Suffix | Example | Meaning |
|---|---|---|
J2 / Q (SKF) | 30311-J2/Q | Pressed steel cage / optimised contact geometry |
A / U / D | 30311-A | Internal design variants from different makers (e.g. FAG A, NTN U, NTN D steep angle) |
Cone / cup | 30311 cone | Tapered bearings are separable; cone (inner) and cup (outer) can be sold separately |
DF / DB / pair | 30311-DF | Matched pairs for preloaded arrangements |
Same bore
Other 55 mm bore bearings
Every standard bearing in this reference with a 55 mm bore, from light to heavy sections.
| Designation | Type | D | B / H |
|---|---|---|---|
| 6011 | Deep groove ball bearing | 90 mm | 18 mm |
| 6211 | Deep groove ball bearing | 100 mm | 21 mm |
| 6311 | Deep groove ball bearing | 120 mm | 29 mm |
| 6411 | Deep groove ball bearing | 140 mm | 33 mm |
| 61811 | Deep groove ball bearing | 72 mm | 9 mm |
| 61911 | Deep groove ball bearing | 80 mm | 13 mm |
| 16011 | Deep groove ball bearing | 90 mm | 11 mm |
| 1211 | Self-aligning ball bearing | 100 mm | 21 mm |
| 1311 | Self-aligning ball bearing | 120 mm | 29 mm |
| 2211 | Self-aligning ball bearing | 100 mm | 25 mm |
| 2311 | Self-aligning ball bearing | 120 mm | 43 mm |
| 7211 | Angular contact ball bearing | 100 mm | 21 mm |
| 7311 | Angular contact ball bearing | 120 mm | 29 mm |
| NU211 | Cylindrical roller bearing | 100 mm | 21 mm |
| NU311 | Cylindrical roller bearing | 120 mm | 29 mm |
| NU2211 | Cylindrical roller bearing | 100 mm | 25 mm |
| NU2311 | Cylindrical roller bearing | 120 mm | 43 mm |
| 22211 | Spherical roller bearing | 100 mm | 25 mm |
| 22311 | Spherical roller bearing | 120 mm | 43 mm |
| 30211 | Tapered roller bearing | 100 mm | 22.75 mm |
| 32011X | Tapered roller bearing | 90 mm | 23 mm |
| 32211 | Tapered roller bearing | 100 mm | 26.75 mm |
| 32311 | Tapered roller bearing | 120 mm | 45.5 mm |
| 51111 | Thrust ball bearing | 78 mm | 16 mm |
| 51211 | Thrust ball bearing | 90 mm | 25 mm |
| 51311 | Thrust ball bearing | 105 mm | 35 mm |
| UCP211 | Pillow block bearing unit | — | — |
Where to buy
Find 30311 at sellers
Search results on independent sellers. We are not affiliated with them, do not earn from these links and do not see their prices or stock. Results mix brands and variants — check the full designation before you order.
About these dimensions. Boundary dimensions follow ISO 355 (metric tapered roller bearings — boundary dimensions), dimension series 03, and are the same for every manufacturer of a standard 30311. Chamfers, load ratings, speed limits and weight depend on the manufacturer and design and are not shown — use the maker's datasheet for engineering decisions. Last checked 9 October 2026. Spotted an error? Tell us.
Learn more
What size is a 30311 bearing?
A 30311 is a tapered roller bearing with a 55 mm bore, 120 mm outside diameter and 31.5 mm total width (T) (55 × 120 × 31.5 mm). These boundary dimensions follow the ISO dimension plan, so they are the same across manufacturers.
What are the cone and cup widths of a 30311?
The cone (inner ring) is 29 mm wide and the cup (outer ring) 25 mm; assembled, the bearing measures 31.5 mm (T). Cones and cups of the same designation are interchangeable between manufacturers that follow ISO 355.
Can I replace 30311 with another bearing of the same size?
Other bearing types can share the same 55 × 120 × 31.5 mm envelope, but a different type has different load directions, speed limits and mounting needs. Same dimensions alone do not make two bearings interchangeable.
Where are the load ratings and speed limits?
They depend on the manufacturer and internal design, so we do not list a single value. Check the datasheet for the exact full designation you intend to use.
Need 30311 data for a whole catalog?
We can help with that.
Normalized specifications, variants and supplier listings for every bearing you sell, with the source behind each value.